The invention relates to a method for identifying critical to quality (CTQ) dependencies in quality function deployment. Quality function deployment (QFD) is a methodology for documenting and breaking down customer requirements into manageable and actionable details. The concept of "houses of quality" has been used to represent the decomposition of higher level requirements such as critical to quality characteristics or CTQ's (also referred to as Y's) into lower level characteristics such as key control parameters or KCP's (also referred to as X's). FIG. 1 depicts a conventional house of quality hierarchy in which high level requirements such as customer requirements are decomposed into lower level characteristics such as key manufacturing processes and key process variables within the manufacturing processes.
Each house of quality corresponds to a stage or level of the process of designing a product. At the highest level, represented as house of quality #1, customer requirements are associated with functional requirements of the product. At the next level of the design process, represented as house of quality #2, the functional requirements of the product are associated with part characteristics. At the next level of the design process, represented as house of quality #3, the part characteristics are associated with manufacturing processes. At the next level of the design process, represented as house of quality #4, the manufacturing processes are associated with manufacturing process variables. While the house of quality design process is useful, it is understood that improvements to this process are needed.